How the Class Mixer builds balanced groups (and keeps friendships)

Splitting a class into balanced groups by hand — for transition, for setting, or just for a fair table plan — is fiddly and easy to get wrong. The Class Mixer does the arithmetic so every group ends up genuinely balanced, then lets you nudge anything you want to change.

How it was built

The mixer uses a scoring algorithm (simulated annealing) that runs entirely in your browser, on a background thread so the page stays responsive. It starts from a rough split and makes thousands of small swaps, keeping the changes that make the groups more balanced and occasionally accepting a worse move to avoid getting stuck. The result is a set of groups that are even across every attribute you care about at once.

It balances ability, behaviour, gender and flags such as Pupil Premium, EAL and SEN simultaneously, and tries to honour friendship links where doing so does not wreck the balance. Because it runs locally, no pupil names are ever sent to a server.

What the balancing is based on

The attributes the mixer spreads — Pupil Premium, EAL, SEN, prior attainment — are the ones schools are routinely asked to consider by the DfE, Ofsted and the EEF when grouping pupils. Spreading disadvantaged and SEN pupils rather than clustering them is widely recommended; the mixer makes that the default rather than an afterthought.

How to use it well

• Enter first names and an initial only — that is all the mixer needs, and it keeps pupil data minimal.
• Set ability and behaviour as simple 1–3 bands; you do not need fine-grained data for the balance to work.
• Add friendship links sparingly — a couple per child the algorithm can satisfy, rather than long lists it cannot.
• Re-run it a few times; each run is slightly different, so you can pick the split you like best.
• Save the result as a class and reuse it in the Seating Plan, Name Picker and Report Writer.

Where your data lives

Everything you type stays in your browser. There is no account and no server-side database — class lists and saved work live in your browser's own storage on the device you are using. You can export a backup or clear everything at any time from the Classes page.